The presence of dopants within an insulating or semiconducting matrix can dramatically alter the electrical characteristics and behavior of a device which incorporates the matrix. Dopants can be electron donors or acceptors which provide additional charge carriers within the matrix. These charge carriers add energy levels within an energy band gap of the semiconducting matrix. The presence of these dopants in the matrix may allow for alteration of certain important electrical characteristics of the device containing the matrix. For example, the dopants may be used to alter the width of a space charge region, which changes the capacitance of the device. The device may retain a “memory” of this capacitance for a period of time.
Devices which exhibit a “memory” of past electrical conditions based on changes in capacitance are called “memcapacitors” or “memcapacitive devices.” Memcapacitive behavior is most strongly evident in nanometer scale devices, where conventional driving voltages can produce large electric potential gradients across the nanometer scale device. These memcapacitors could potentially be used for high density data storage, circuit calibration, or to provide self programming, fuzzy logic, or neural learning capabilities.
Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.